It should be noted also that had Bo not shown up Dinn would have died. First by the Great Value Grevious. And if he had managed to beat it and gotten to the water successfully. By drowning on the lake bed. Kind of makes me wonder what the motives of the Armorer really are. I mean if Dinn was to become Mandalore (I don't think he will but that is just my OP) The Armorer would lose defacto control of the sect. Dinn would flat out rank her and could change doctrine. She is a cult leader and can't have that. You can't have people go against the rules of a cult. When you look back on everything all of her advice and decisions are totally sus.
I don't think the Armorer would lose control of the sect, because it appears pretty clear that Mandalorian armorers fill the traditional role of clan elder and lorekeeper, whereas Mand'alor is a meta-leader
over the clans. Totally different level of authority.
It also sounds like even outside the Children of the Watch, bathing in the
Living Waters is the traditional rite of passage for a Mandalorian youth, combining aspects of baptism, adult rite of passage, and knighting ceremony. Bo-Katan clearly seems to be mentioning it in that context, and that's even with her upbringing being
New Mandalorian. Also notice the shoreline induction ceremony of the Children clearly mirrors it, and almost certainly would have been performed in the Mines if it was still possible.
Seriously, Din coming back to the Children with news that the Living Waters are
intact and the surface of Mandalore is blasted but inhabitable is going to be a HUGE, HUGE, HUGE deal. Mandalore *already rebuilt from orbital devastation* at least once before in its history, the only reason they haven't been waiting to come back and rebuild again was the belief that the Empire did something that would permanently poison the surface.
Edit: Also, Disney definitely did their homework, with the massive blast craters of trinitite glass.